Automatic pattern tracing systems

ABSTRACT

An automatic system for tracing a pattern depicted on a sheet of drawing comprises a detector operative to determine the presence or absence of the pattern to convert it into an electric signal, tracing direction detecting means responsive to the electric signal to judge whether the pattern is to be traced or not so as to provide a signal for moving the detector in the tracing direction, a driving mechanism responsive to the signal from the tracing direction detecting means to relatively move the detector in a predetermined direction by a predetermined distance and means to generate a digital signal corresponding to the tracing direction or a tracing spot, said detector detecting the information regarding the presence or absence of the pattern in an area close to the pattern to be traced thus continuously tracing the same.

United States Patent Takahashi et a1. [45] June 20, 1972 541 AUTOMATICPATTERN TRACING 3,245,036 4/1966 Grottrup ...250/202 x SYSTEMS 3,429,9892/1969 Stockdale ..250/202 x [72] inventors: Tadashi Takahashl;Masatoshi Miyazaki, both of Sendai; Yasuhiko Ogawa, Natori; TadashiSato; Kazuhiko Kakuta, both of Tokyo, all of Japan [73] Assignee: lwatsuElectric Company, Ltd., Suginamiku, Tokyo, Japan [22] Filed: May 28,1970 {21] Appl. No.: 41,297

[30] Foreign Application Priority Data May 31, 1969 Japan ..44/4Z07l May31, 1969 Japan... ..44/42072 [52] US. Cl. ..340/ 146.3 AE, 250/202 [51]lnt.Cl. ..G06k9/16 [58] FieldofSearch ..250/202,219QA;318/577; 340/1463AE; 178/68 [56] References Cited UNITED STATES PATENTS 2,816,705 12/1957Thrall et a1. ..250/202 20 PROCESSING CKT Primary Etaminer-Maynard R.Wilbur Assistant ExaminerLeo H. Boudreau Attorney-Chittick, Pfund,Birch, Samuels & Gauthier [57] ABSTRACT An automatic system for tracinga pattern depicted on a sheet of drawing comprises a detector operativeto determine the presence or absence of the pattern to convert it intoan electric signal, tracing direction detecting means responsive to theelectric signal to judge whether the pattern is to be traced or not soas to provide a signal for moving the detector in the tracing direction,a driving mechanism responsive to the signal from the tracing directiondetecting means to relatively move the detector in a predetermineddirection by a predetermined distance and means to generate a digitalsignal corresponding to the tracing direction or a tracing spot, saiddetector detecting the information regarding the presence or absence ofthe pattern in an area close to the pattern to be traced thuscontinuously tracing the same.

2 Claims, 7 Drawing Figures PREVIOUS 101 F l G. 7 Descmmfj VALUE m.NATING GK" 1 2 222 K c ean L O6 @zm %w r 22 MEAN VALUE lat- I I5 I I6ACING r "65.551223 r c u VALUE VAEGE T 108 109 no In MEMORY venom @ORYIMEMORY TRACING DIRECTION INGFOR- BIDDING DI- o0 TRACING FORBIDDINGDIRECTION PREVIOUS VALUE REG TRACING DIRECTION PREVIOUS TO INPUT- OUTPUTCKT I5 VALUE REG PATENTEDJUH20 I972 SHEET 2 of 4 3, 671 .937

TO PROCESSING CIRCUIT 22 FIG. 2

TADASHI TAKAHASHI MASATOSHI MIYAZAKI YASUHIKO OGAWA INVENTORS TADASHISATO KAZUHIKO KAKUTA mwm lwtem- ATTORNEY {MEMORY] ueuonfl -LMEMORYJLMEMORY| PA'TENTEnJunzo 1912 3,671,937

saw u or 4 20 PREVlQUS |O| G 7 T; DESCRM VALUE RET.

AMPL NATING CKT 1 l T l rs giTr' @221 I03 usuonv 2 vAru E o ET IO i I08I09 no Hl TRALING TRACING TRACING TRACING wags %'J:. :J.:2s z'm a r" MAR VALUE VALUE VALUE VALU ED CING F'OR' BIDDING DI- on I mu VALUE comm-I23 DET RATOR n4 n2 I TRACING psasfasms r:;2$::s DIRECTION DIRECTION PRv 0u MEMORY MEMORY VALUE REG I24 I25 TRACING omecnou l PREVIOUS VALUEREG H3 I22 I 3 +1 TO INPUT-OUTPUT CKT l5 TADASHI TAKAHASHI MASATOSHIMIYAZAKI YASUHIKO OGAWA INVENTORS TADASHI SATO KAZUHIKO KUTA I ATTORNEYAUTOMATIC PA'I'I'ERN TRACING SYSTEMS CROSS REFERENCE TO RELATEDAPPLICATIONS This application is related to applications filed of evendate herewith, Ser. Nos: 41,172, 41,296, 41,291 and 41,471, all assignedto the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates to an automaticpattern tracing system and more particular to a system for automaticallytracing a pattern depicted on a sheet of drawing to convert it into adigital signal.

In many fields of engineering it is desirable to automatically tracepatterns in the form of various curves, segments and the like depictedon a sheet of drawing to convert them into electrical digital signals.Such requirements arise when various waveforms such as, cardiograms,brain waves, earthquake waves and the like, for example, are to beautomatically analyzed to identify their patterns. Further, whensupplying various data curves to a standard electronic computor, atpresent such data curves are converted into technical terms with a greatlabor and time and the converted information is then supplied to theinput device of the computor.

SUMMARY OF THE INVENTION It is therefore an object of this invention toprovide an automatic pattern tracing system which functions toautomatically trace various patterns depicted on a sheet to providedigital outputs of the traced information.

A further object of this invention is to provide an automatic patterntracing system providing information directly useable as the inputs toelectronic computers.

Still further object of this invention is to provide a novel automatictracing system which can correctly trace the pattern always along thedirection thereof in response to the detected signal.

Another object of this invention is to provide an automatic patterntracing system which can determine a particular one of a plurality ofdetector outputs which is to be traced.

Still another object of this invention is to provide an automaticpattern tracing system which repeats the tracing operation for aselected portion of the pattern.

Further object of this invention is to provide a novel system applicableto a function generator which generates an electric signal correspondingto the configuration of a curve.

According to this invention, the presence or absence of a pattern at agiven point on a drawing is detected by means of a detector and thedetected pattern is converted into an electrical signal which isutilized to determine in which direction the pattern is to be traced.According to this determination or judgement a signal is generated toshift the detector in the direction to be traced. Responsive to thissignal a drive means shifts the drawing or detector over a predetermineddistance in the desired direction thus tracing the pattern on thedrawing. Such a partial tracing operation is repeated to trace theentire pattem.. Each partial tracing operation generates a digitalsignal corresponding to a tracing direction or tracing point. Memorymeans is provided to memorize the direction to be traced and thedirection along which the tracing is forbidden for each tracingoperation. The stored information is used to determine the direction tobe traced, forbidden direction and directions other than these twodirections, thus enabling to determine an appropriate tracing direction.

BRIEF DESCRIPTIONS OF THE DRAWINGS The invention can be more fullyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is a block diagram of one embodiment of an automatic patterntracing system constructed according to the principle of this invention;

FIG. 2 is a perspective view, partly in section, of a detector utilizedin the system shown in FIG. 1;

FIG. 3 is a perspective view of the driving mechanism shown in FIG. 1showing the relationship between a recording paper carrying a pattern,and the detector;

FIG. 4 is a diagram to explain the relationship between the roundscanning operation of the detector, the detector output and the outputfrom a processing circuit when a curve depicted on the recording paperis traced;

FIG. 5 shows one example of predetermined reference directions utilizedto determine the pattern tracing direction of the detector;

FIG. 6 is a diagram to show the relationship between the round scanningoperation of the detector, the detector output and the output from theprocessing circuit when a curve depicted on a recording paper includes abranch line, and

FIG. 7 shows a block diagram wherein respective program operations ofthe system shown in FIG. 1 are replaced by hardware.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 of theaccompanying drawing, the entire system of this invention is shown ascomprising a processing means 10, a sensor 20 and a driving mechanism30, the sensor reading the positional information of a pattern to betraced and depicted on a sheet of drawing to send the informa tion tothe processing means 10. The processing means 10 suitably processes theinformation so as to operate the driving mechanism 30 in accordance withthe resulting digital signal thus shifting sensor 20 a predetermineddistance in a predetermined direction. Then the positional informationof the pattern at the shifted position is again read by sensor 20. Theabove described cycle of operations is repeated to automatically tracethe entire pattern. The digital signal produced at each time is via line19 to an electronic computor and the like, not shown.

The detail of each component part will now be described. The sensor 20comprises a detector 21 to convert the concentration, that is, the whiteand black tones of the pattern into electric signals and a processingcircuit 22 to suitably process electrically the output from the detector21. In this embodiment, the detector 21 comprises a photoelectricdetector of the construction shown in FIG. 2. As shown in FIG. 2, thedetector 21 comprises a cylindrical casing 24 of opaque material havinga top closed end 25 and a frustoconical bottom portion having a bottomopening 26. Inside the casing 24 is formed a cylinder 27 concentricallywith casing 24. One end of the cylinder 27 is secured to the upper end25 of the casing 24 while the opposite end is terminated at a pointslightly above the bottom opening 26. Within cylinder 27 is disposed alight receiving element or a photoelectric converting element 28 and alight source 29 is disposed in a space between cylinder 27 and casing24. Accordingly, when sensor 20 is in its operating state, light isprojected toward outside from source 29 through opening 26. Thephotoelectric converting element 28 operates to receive the lightprojected upon a point being scanned on the pattern and reflectedtherefrom and transforms it into an electric signal.

The processing circuit 22operates to shape the waveform of the electricsignal supplied from photoelectric converting element 28 to descriminatewhite and black to provide a binary output of l or 0, the formercorresponding to white and the latter to black. These signals arecontinuously supplied to processing means 10 from sensor 20.

The driving mechanism 30 comprises two stepping motors 31 and 32 and acontrol circuit 33 to control stepping motors in response to a signalsupplied from processing means 10, the detail of the driving mechanismbeing shown in FIG. 3.

As shown in FIG. 3 the driving mechanism comprises a rotary drum 34having a shaft 35 and a recording paper 36 described with a pattern tobe traced by the detector 21 is passed about the periphery of rotarydrum 34. The rotary drum 34 is driven by stepping motor 31 via a belt 38to drive the recording paper 36 in a direction indicated by an arrow (Xaxis). The recording paper 36 is moved between a supply reel 40 and atake up reel 41 via guide rollers 42 and 43 which function .to cause therecording paper 36 to directly engage the peripheral surface of rotarydrum 34. An endless belt 46 is passed around a pair of spaced apartpulleys 44 and 45 and the detector 21 is secured at a predeterminedposition along the length of belt 46. It is to beunderstood that thedetector 21 is disposed so that its bottom opening 26 is directed towardthe axis of rotary drum 34 and that it is moved along the surface of thedrum 34 in a direction indicated by an arrow (Y axis). The pulley 45 isdriven by the Y axis stepping motor 32. Responsive to one pulse from thecontrol circuit 33 each of the stepping motors 31 and 32 steps adefinite angle to move recording paper 36 and detector 21 by a definitedistance. Thus, stepping motors 31 and 32 effect relative movement ofabout 0.1 mm, for example, between recording paper 36 and detector 21 ateach step. Thus, it will be seen that the driving mechanism has thesame'construction and function as the prior art incremental X, Yplotter.

With reference again to FIG. 1, the processing means comprises a programmemory 11 storing a program necessary for the scanning and tracingoperations of the pattern, a decoder 12 to read the program supplied bythe program memory 11, .a sequence control circuit 13 to control theoperating sequence of various component parts to be described later anda group of registers 14 comprised by a plurality of serially connectedshift registers. The majority of these shift registers function totemporarily store a signal from an input-output circuit 15 while theremaining shift registers function to store constants,- modes, memoryaddresses, return addresses and the like. These shift registers operatein response to a sequence control signal supplied from the sequencecontrol circuit 13 described above. An operation circuit 16 is providedto perform such operations and processings as addition, subtraction,logical product and logical.addition, etc., in response to a signalsupplied from the group of shift registers 14. The type of theoperations is selected by an operation sequence control signal suppliedfrom the sequencecontrol circuit 13. Acontrol counter 17 is provided todesignate the addres in the memory 11 storing the program. Thus thecontrol counter 17 contains the content of a field representing thejumping address at the time of jumping order but the contents of thereturn address shift register in the group of registers 14 when theorder is returned from a subroutine. There is also provided controlpanel 18 ineluding various switches and indicators necessary foroperating the system.

When a start switch (not shown) of a control panel 18 is depressed thevarious components shown in FIG. 1 commence to operate so that thedetector 21 of sensor 20 begins to trace the pattern according to theprogram stored in the memory 1 1. Detector 21 is driven by the drivingmechanism 30 to perform a round scanning operation of a substantiallysquare area including the pattern on the recording paper 36 which is tobe traced. As used herein the term a round seaming means a scan patharound the periphery of a designated elemental area. Such a roundscanning can be performed by the proper control of Y stepping motors 31and 32 of the driving mechanism 30 provided by the control circuit 33.The number of spots to be plotted by the round scanning operation can beselected to any value by the command from the control panel 18. In anexample shown in FIG. 4, 10 spots are plotted in the direction of X axisand 10 spots are plotted in the direction of Y axis. Accordingly, atotal of 40 spots are plotted at each round scanning operation.

' A tracing operation performed on a typical pattern on the recordingpaper 36 is as follows.

FIG. 4 shows a diagram to explain the operation of the detector 21 totrace a pattern, e.g. a curve 47 on the recording paper 36. P,, P; Pshow scanning spots as the detector 21 performs a round scanningoperation of the pattern on the recording paper by being moved along theperiphery of a square area. White dots and black dots represented onpositions corresponding to these scanning spots show the resultsobtained by judging the output of the detector 21 generated by scanningthese spots, by theoperation of the processing circuit 22. Moreparticularly, a white dot at a spot P, shows that the result provided byjudging the output from detector 21 corresponding to this spot by meansof processing circuit 22 is white". In the same manner, a black dot at aspot P shows that the result provided by judging the output fromdetector 21 corresponding to this spot by means of the processingcircuit 22 is black. A dot shows that. there is present a pattern ofsame type at that spot. Accordingly, in the illustrated example, theblack dots show that the pattern includes spots P P P and spots P P andP It is clear that in this case the curve 47 is traced by these twogroups of information and by information obtained during the previousscanning. These two groups of information are supplied to the group ofregisters 14 from the processing circuit 22 via the input-output circuit15 of the processing means 10 and are stored in these registers. Thesegroups of information stored in the registers 14 are operated andprocessed by the operation circuit 16 according to the prescribedprogram. First, of said two groups of spots, spots P9 and P near thecenter of curve 47 are detennined. These spots near the center can bedetermined by averaging the maximum value and the minimum value of thenumbers of the spots of respective groups and the value obtained isstored in registers 14. Spots P and P represent the direction of curve47 and either one of them represents the direction of tracing. In orderto determine which one of the information spots at the center ofrespective groups represents the direction of tracing, the direction oftracing in the previous scanning is stored in the registers 14.Consequently, the direction most close to the direction of previousscanning is judged as the direction of tracing. For this reason, in thesucceeding scanning operation this vdirection is treated as thedirection of previous scanning. The direction in which the tracing isforbidden is treated in the same manner. The center of the abovedescribed round scanning is considered to lie generally on a curve 47. 7

With reference now to FIG. 5, a method of judging the direction alongwhich the detector 21 is to be traced will be described in thefollowing. As shown in FIG. 5, eight reference directions 1 to 8 arepredetermined. These directions are designated by codes 1", 2 8 in theclockwise direction. If it is assumed now that the spot P represents thedirection of scanning, this spot is made to correspond to referencedirection 1 and an output corresponding to this 1 direction is sent tocontrol circuit 33 of driving mechanism 30 from registers 14 viainput-output circuit 15,

and the positional information of spot 17 is stored in register.

group 14. In FIG. 4, since there are 40 spots to be plotted it isnecessary to store the number of these spots, and the stored number istreated to represent the direction of previous tracing during thesucceeding scanning operation.

FIG. 6 is a diagram to explain the tracing operation where curve 47includes a branch line 48. In this case, information groups are obtainedrepresenting that the pattern lies on spots P P P P P P and P P P As aresult, like the foregoing description with reference to FlG. 5 theprocessing means 10 provides information of spots P P and I. which areat the centers of the above described three groups of information andthese data are compared with those of the previous scanning to determinewhich spot corresponds to the direction of tracing whereby to send asignal to the driving mechanism 30 for performing the tracing operationin the tracing direction thus determined. In this case, in addition tothe information regarding the direction to be traced and the directionthat has been traced an information regarding spot P is obtained whichshows that there is a branched or crossing curve 48, thus requestingprocessing means 10 to perform another operation. If the tracingdirections at respective scanning operations are represented by codessuch as 2, 2, l, 3,1 these data will represent the configuration of thecurve.

The above described operation can be more fully understood from thefollowing description regarding the block diagram shown in FIG. 7wherein various operations processed according to a program in the caseof FIG. 1 are replaced by hardware and wherein the processing means 10and a portion of sensor 20 are shown in detail.

In FIG. 7, source of light 27 (See FIG. 2) of detector 21 is connectedto a source of current 221 in the processing circuit 22 which furtherincludes a DC amplifier 222 and a discriminating circuit 223 responsiveto the output of amplifier 222 for discriminating white and black. Thedescriminating circuit 223 provides an output l for a white spot and anoutput 0 for a black spot. The output from discriminating circuit 223 issupplied to a previous value retainer 101. The output is also sent to acomparator circuit 102 which compares the output from previous valueretainer 101 and the output from discriminating circuit 223. When thetracing information changes from white to black as a result ofcomparison of these two outputs a l output will be sent to conductor 103whereas when the information changes from black to white a l output willbe provided for conductor 104. The 1 output on conductor 103 is appliedto a memory 105 whereupon the memory 105 stores the positionalinformation of detector 21 from a position counter 106. This conditioncorresponds to the movement of detector 21 from spot P to spot P-,, forexample, in FIG. 6. Upon further movement of detector 21, comparatorcircuit 102 again detects the change of from black to white to provide al output on conductor 104, this output being supplied to a mean valuedetector 107. This condition corresponds to the movement of the detectorfrom spot P to spot P in FIG. 6. Accordingly, the mean value detector107 operates to calculate the mean value of the previous positionalinformation of detector 21 which has been stored in memory 105 at thisstage and the present positional information of detector 21. In thismanner, the positional information of a spot near the center while thedetector 21 is detecting black is determined. This central spotcorresponds to spot P for example, in FIG. 6. This mean value is storedin one of memories 108 through 111, for example 108. When another meanvalue information is sent during the round scanning operation suchinformations is stored successively in memories 109, 110 and 1 l l Aportion of the mean value information is also supplied to a comparator112 where it is compared with an information from a tracing directionprevious value register 1 13 and an information value from a tracingforbidding direction previous value register 114 and the results ofcomparison are successively sent to tracing direction compared valuememories 115 through 118 and tracing forbidding direction compared valuememories 119 through 122 to be stored therein. Information values storedin respective tracing direction compared value memories 115 through 118are sent to a minimum value detector 123 which detects the minimumvalue. Among the mean value information stored in memories 108 through111, an information value corresponding to the minimum shows a valuemost close to the direction of the previous tracing. This information issent to the tracing direction memory 124 to be stored therein. Similarlythe minimum value detector 123 operates to detect the minimum value ofthe information stored in tracing forbidding direction compared valuememories 119 through 122 to determine the information most close to thatof the previous tracing forbidding direction. This information is sentto a tracing forbidding direction memory 125 to be stored therein. Theinformation representing the tracing direction is approximated to one ofeight reference directions described before and is then sent toinput-output circuit via lines 126 and 127. As shown in FIG. 1, theoutput from the input-output circuit 15 is supplied to an externalcircuit over conductor 19 and also to the control circuit 33 of thedriving mechanism 30. As a result, either one of stepping motors 31 and32 is caused to step to move one step either detector 21 or recordingpaper 36. In this case, one step of motors and one step of tracing arenot equal.

At each round scanning operation the contents of the previous valueregisters 113 and 114 are changed and the above described operations arerepeated to trace a continuous curve.

Although in this embodiment, a photoelectric detector has beenillustrated, it will be clear that various other types of detectors mayalso be used including a well known magnetic detector and an electricdetector depending upon the characteristics of the sheet of drawing andthe property of the printing ink.

Further, to simplify the construction of the detector movable on thesurface of the drawing, the photoelectric converting element and thelight source may be held stationary at points remote from the read-outhead movable on the drawing and the head may be connected to the lightsource and the photoelectric converting element through light guidesmade of optical fiber glass.

With a single detector of the type described above it is necessary tomove it successively for scanning. Where a plurality of discretedetectors are arranged on the periphery of a square and are operatedsequentially for each scanning operation it becomes unnecessary to movethe detector around a square by mechanical means.

Further instead of moving the detector around a square it can also bemoved along the periphery of a hexagon, pentagon or circle.

What is claimed is l. The method of automatically tracing a pattern on asurface by alternately performing a round scan of the periphery of anelemental area and moving the center of said round scan an incrementaldistance comprising the steps of:

performing a round scanning operation along the periphery of anelemental area on said surface, each scan including sensing a regularline of spots on said periphery for detecting the presence or absence ofsaid pattern, from spot to spot;

storing for each said scan digital code information in response todetected changes in said presence or absence of pattern, said codeidentifying the location on said line of spots of each branch of saidpattern traversed by said scan;

comparing a stored previous value tracing direction code with saiddigital code information and storing a tracing direction compared value;comparing a stored previous value tracing forbidden direction code withsaid digital code information and storing a tracing forbidden directioncompared value;

detecting the minimum values of respective stored tracing direction andtracing forbidden direction compared values;

storing from said digital code information for said branches those codescorresponding to said minimum values as a tracing direction code andtracing forbidden direction code, respectively; moving the center ofsaid round scanning operation over the surface containing said patternby said incremental distance corresponding to an adjacent position forsaid elemental area and in one of a set of predetermined directions, theselected direction corresponding to said stored tracing direction code;transferring said tracing direction code and said tracing forbiddendirection code to up-date the respective said stored previous valuecodes at each said scan; and

repeating alternately said performing said round scanning operation andsaid moving said center said incremental distance to trace said pattern.

2. The method of claim 1 wherein the step of storing said digital codeinformation in response to detected changes in said presence or absenceof pattern includes:

detecting the adjacent digital values of the spots in one of said scanswhere said pattern is detected to change from white to black and fromblack to white and supplying the mean value of said adjacent digitalvalues as said digital code information to be stored.

1. The method of automatically tracing a pattern on a surface byalternately performing a round scan of the periphery of an elementalarea and moving the center of said round scan an incremental distancecomprising the steps of: performing a round scanning operation along theperiphery of an elemental area on said surface, each scan includingsensing a regular line of spots on said periphery for detecting thepresence or absence of said pattern, from spot to spot; storing for eachsaid scan digital code information in response to detected changes insaid presence or absence of pattern, said code identifying the locationon said line of spots of each branch of said pattern traversed by saidscan; comparing a stored previous value tracing direction code with saiddigital code information and storing a tracing direction compared value;comparing a stored previous value tracing forbidden direction code withsaid digital code information and storing a tracing forbidden directioncompared value; detecting the minimum values of respective storedtracing direction and tracing forbidden direction compared values;storing from said digital code information for said branches those codescorresponding to said minimum values as a tracing direction code andtracing forbidden direction code, respectively; moving the center ofsaid round scanning operation over the surface containing said patternby said incremental distance corresponding to an adjacent position forsaid elemental area and in one of a set of predetermined directions, theselected direction corresponding to said stored tracing direction code;transferring said tracing direction code and said tracing forbiddendirection code to up-date the respective said stored previous valuecodes at each said scan; and repeating alternately said performing saidround scanning operation and said moving said center said incrementaldistance to trace said pattern.
 2. The method of claim 1 wherein thestep of storing said digital code information in response to detectedchanges in said presence or absence of pattern includes: detecting theadjacent digital values of the spots in one of said scans where saidpattern is detected to change from white to black and from black towhite and supplying the mean value of said adjacent digital values assaid digital code information to be stored.